Methylenetetrahydrofolate reductase (MTHFR) catalyzes the synthesis of 5-methyltetrahydrofolate, the methyl donor for remethylation of homocysteine to methionine. The C677T MTHFR polymorphism is associated with mild hyperhomocysteinemia, but only in the presence of low folate status. Because MTHFR contains flavin adenine dinucleotide (FAD) as a prosthetic group, riboflavin status may also influence homocysteine metabolism. The objective of this study was to examine the association between riboflavin status and fasting plasma total homocysteine (tHcy) concentration while also considering MTHFR C677T genotype and folate status. The study was conducted using fasting plasma samples (n = 450) from the fifth examination of the Framingham Offspring Study cohort. All persons with the TT genotype and age- and sex-matched sets of individuals with the CT and CC genotypes were selected for determination of plasma riboflavin and flavin mono- and dinucleotide levels. Plasma riboflavin was associated with tHcy concentrations, but the association was largely confined to persons with plasma folate <12.5 nmol/L and TT genotype. In these persons, the mean tHcy among individuals with riboflavin levels <6.89 nmol/L was 14.5 micromol/L, whereas the mean tHcy for those with riboflavin > or = 11 nmol/L was 11.6 micromol/L (P-trend <0.03). Plasma flavin nucleotides were unrelated to tHcy concentrations. Our data suggest that riboflavin status may affect homocysteine metabolism, but only in a small segment of the population who have both low folate status and are homozygotes for the MTHFR C677T mutation.
BackgroundDiabetic kidney disease (DKD) is a major burden in elderly patients with type 2 diabetes (T2DM). Low estimated glomerular filtration rate (eGFR+, < 60 mL/min/1.73 m2) and albuminuria (Alb+) are essential for the diagnosis of DKD, but their association with clinical variables and quality of care may be influenced by ageing.MethodsHere we investigated the association of clinical variables and quality of care measures with eGFR+ and Alb+ in 157,595 T2DM individuals participating to the Italian Association of Clinical Diabetologists (AMD) Annals Initiative, stratified by age.ResultsThe prevalence of eGFR+ and Alb+ increased with ageing, although this increment was more pronounced for low eGFR. Irrespective of age, both the eGFR+ and Alb + groups had the worst risk factors profile when compared to subjects without renal disease, showing a higher prevalence of out-of target values of HbA1c, BMI, triglycerides, HDL-C, blood pressure and more complex cardiovascular (CVD) and anti-diabetic therapies, including a larger use of insulinIn all age groups, these associations differed according to the specific renal outcome examined: male sex and smoking were positively associated with Alb+ and negatively with eGFR+; age and anti-hypertensive therapies were more strongly associated with eGFR+, glucose control with Alb+, whereas BMI, and lipid-related variables with both abnormalities. All these associations were attenuated in the older (> 75 years) as compared to the younger groups (< 65 years; 65–75 years), and they were confirmed by multivariate analysis. Notably, Q-score values < 15, indicating a low quality of care, were strongly associated with Alb+ (OR 8.54; P < 0.001), but not with eGFR+.ConclusionsIn T2DM patients, the prevalence of both eGFR and Albuminuria increase with age. DKD is associated with poor cardiovascular risk profile and a lower quality of care, although these associations are influenced by the type of renal abnormality and by ageing. These data indicate that clinical surveillance of DKD should not be unerestimated in old T2DM patients.Electronic supplementary materialThe online version of this article (10.1186/s12877-018-0732-4) contains supplementary material, which is available to authorized users.
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